Introduction: The incidence, survival, and propensity for nodal metastasis in early-stage gastric signet ring cell carcinoma have not been defined in the United States. These data are critical determinants for treatment allocation.
Methods: Cases of gastric signet ring cell carcinoma were extracted from the national SEER database for the years 2004-2013. Age-standardized incidence was derived. Survival was calculated using the Kaplan-Meier method. Univariate and multivariate analyses were performed to identify predictors of nodal metastasis. Exclusion criteria included neoadjuvant radiotherapy and lack of histologic or nodal data.
Results: A total of 10,624 cases were initially identified. The analysis cohort included 506 cases with early T-stage N0M0 disease following exclusions. The incidence was 0.094 per 100,000 person-years. The 5-year survival rate was 82.8%. Tumor stage (p < 0.001) and size (p < 0.001) were independent predictors of nodal metastasis. The incidence of nodal involvement for T1a tumors <2 cm was 5.4% (p < 0.004).
Conclusion: The incidence of potentially resectable signet ring gastric carcinoma has not changed significantly over the past decade. While presenting with predominantly high-grade histology, early T-stage disease has a high survival rate. Small T1a tumors have low rates of nodal metastasis, suggesting that an endoscopic resection could be considered in this subset.
Keywords: Endoscopic mucosal resection; Endoscopic submucosal dissection; Gastrectomy; Gastric cancer; Gastric signet ring carcinoma.